499 PROLONGED MATERNAL EXERCISE IN LATE GESTATION-FETALRESPONSES NICOLE GLENN1, GREGORY DAVIES2, SARAH CHARLES-WORTH1, LARRY WOLFE1, 1Queen’s University at Kingston, Physical andHealth Education, Kingston, Ontario, Canada 2Queen’s University atKingston, Obstetrics and Gynecology, Kingston, Ontario, Canada

OBJECTIVE: To examine fetal responses to prolonged cycling in lategestation.

STUDY DESIGN: Seventeen active pregnant women (gestational age, 34-39weeks) experiencing uncomplicated pregnancies completed 40 minutes ofupright cycling at 85% of their measured ventilatory anaerobic threshold (meanmaternal HR of 138 ± 1 beats/minute). Cardiotocography was recorded for 20minutes prior to and 20 minutes immediately following maternal exercise. Four10 minute cardiotocography segments were created and analysed in a random-ized blinded fashion in accordance with the guidelines published by theNational Institute of Child Health and Human Development (1997). Birthoutcome data were collected from hospital records.

RESULTS: Prolonged maternal exercise in late gestation resulted inminimal changes in fetal heart rate characteristics. In this regard, fetal heartrate baseline was significantly elevated in the first 10 minutes post-exercise(139 ± 3 beats/min) compared to the pre-exercise baseline (133 ± 2 beats/min) and returned to pre-exercise values in the second 10minute segment post-exercise (133 ± 2 beats/min). There were no cases of post-exercise bradycardiaor tachycardia. There was a significant reduction in fetal movements in the first10 minutes post-exercise period compared to the pre-exercise values (one-tailedStudent-t Statistic p < 0.05). There were no significant effects on fetal heart ratevariability, or the frequency of fetal heart rate accelerations or decclerations.All women had favourable birth outcomes and no neonates displayedcharacteristics of growth restriction (birth weight < 2500g).

CONCLUSION: Our findings support the hypothesis that prolonged,moderate intensity exercise is well tolerated by pregnant women and theirfetuses. Supported by Canadian Forces Personnel Support Agency.

500

501 A ROLE FOR HEAT SHOCK PROTEIN 70 IN SPONTANEOUS PARTURI-TION AT TERM TINNAKORN CHAIWORAPONGSA1, JIMMY ESPINOZA1,YEON MEE KIM1, RICARDO GOMEZ1, BO YOON2, EMMANUEL BUJOLD3,ROBERTO ROMERO1, 1Perinatology Research Branch, NICHD/NIH/DHHS, Detroit, MI 2Seoul National University, Seoul, South Korea 3WayneState University, Obstetrics and Gynecology, Detroit, Michigan

OBJECTIVE: The role of progesterone as a ‘‘pro-pregnancy’’ hormone hasbeen recognized for more than 60 years. Yet, the traditional view has been thathuman parturition is not dependent on a progesterone withdrawal because theconcentrations of this hormone do not change prior to labor. Recent evidencesuggests that 17 alpha-hydroxyprogesterone caproate can prevent preterm birthin patients at risk, an effect that may be pharmacological in nature, oralternatively, treat a premature functional ‘‘progesterone withdrawal’’. Wepropose that heat-shock proteins (HSP) play a key role in suspendingprogesterone action as two members of this family can bind the progesteronereceptor and block hormone action.

STUDY DESIGN:A cross-sectional study was conducted in normal pregnantwomen of the following groups: 1)midtrimester women who underwent geneticamniocentesis and delivered at term (n = 72); 2) term with intact membranes,in labor (n = 48); and 3) term with intact membranes, not in labor (n = 23).HSP70 concentrations in amniotic fluid were determined using a sensitive andspecific immunoassay. Non-parametric statistics were used for analysis. A p value< 0.05 was considered statistically significant.

RESULTS: 1) HSP70 was detectable in 74% (106/143) of amniotic fluidsamples; 2) The median amniotic fluid HSP70 was significantly higher at termthan those in the mid-trimester (term no labor, median 34.9 ng/ml, range 0-78.1ng/ml vs midtrimester, median 6.6 ng/ml range, 0-20.8 ng/ml; p < 0.001);3) spontaneous labor at term was associated with a significantly higher medianamniotic fluid HSP70 concentration (term in labor, median 60.7 ng/ml, range0-359.9 ng/ml vs. term no labor, median 34.9 ng/ml, range 0-78.4; p = 0.02).

CONCLUSION: 1)HSP70 concentrations in amniotic fluid are increased inspontaneous labor at term; 2) We propose that HSP70 plays a role in generatinga suspension of progesterone action in the absence of a ‘‘progesteronewithdrawal’’.

502 MANAGEMENT OF PREECLAMPTIC OLIGURIA – A NONINVASIVEMANAGEMENT PROTOCOL JAMES SCARDO1, SUNEET CHAUHAN1,STEVE VERMILLION2, GENE CHANG2, 1Spartanburg Regional MedicalCenter, Spartanburg, SC 2MedicalUniversity of SouthCarolina, Charleston, SC

OBJECTIVE: To prospectively evaluate the utility of a nonivasive protocol ofmanagement of preeclamptic oliguria.

STUDY DESIGN: Prospective observational study of preeclamptic oliguriamanagement guided by nonivasive hemodynamic monitoring. Over a 4 yearperiod at a Regional Perinatal Center, patients with preeclampsia (strict criteria)complicated by oliguria ( < 30 cc urine output/hr foley catheter for 2 hours)unresponsive ( < 30 cc/hr) to 500 cc isotonic fluid bolus The managementprotocol was as follows: If systolic blood pressure > 139 mm Hg or diastolicBP > 89 mmHg, nifedipine (30 mg long acting) was given orally. If after 1 hour,UO<30 cc/hr, noninvasive hemodynamic assessment was performed bythoracic electrical bioimpedance. If cardiac output (CO) < 5.0 liters/minute,further afterload reduction with nifedipine (10 mg short acting) was given. Ifcardiac output > 5.0 l/min, renal dose dopamine (3 micrograms/kg/min) wasinstituted. If unresponsive to above and thoracic fluid conductivity(TFC) < 0.065 fluidic ohms, 500 cc fluid bolus repeated with clinical discretion.

RESULTS: 14 patients met entry criteria with majority (11/14; 78%) beinghypertensive. All patients responded favorably to the above protocol. 11 patientswere hypertensive and 45% (5/11) responded to the initial long actingnifedipine. The remaining 6 (55%) hypertensive patients with oliguria, requiredfurther afterload reduction. 3 patients were not hypertensive. 1/3 non-hypertensive patients had CO< 5.0 l/min and responded to afterload reduction.The remaining 2 normotensive patients had CO > 5.0 l/min and responded torenal dose dopamine.

CONCLUSION: Preeclamptic oliguria should seldom require invasivehemodynamicmonitoring. If preeclamptic oliguria is present with hypertensionafter fluid challenge, afterload reduction may be acceptable therapy. If

December 2003Am J Obstet Gynecol

S196 SMFM Abstracts

PROLONGED EXERCISE IN LATE GESTATION-MATERNAL RESPONSESNICOLE GLENN1, GREGORY DAVIES2, SARAH CHARLESWORTH1,LARRY WOLFE1, 1Queen’s University at Kingston, Physical and HealthEducation, Kingston, Ontario, Canada 2Queen’s University at Kingston,Obstetrics and Gynecology, Kingston, Ontario, Canada

OBJECTIVE: To examine the maternal responses to prolonged cycling inlate gestation.

STUDY DESIGN: Seventeen active pregnant women (PG, gestational ages34-39 weeks) experiencing uncomplicated pregnancies completed 40 minutesof upright cycling at 85% of their measured ventilatory anaerobic threshold(mean maternal HR of 138 ± 1 beats/minute). A non-pregnant control group(CG, n = 10) completed the same exercise test (mean heart rate of 126 ± 2beats/min). Heart rate and respiratory responses were measured continuouslyat rest and during exercise. Tympanic temperature was measured during rest, at10-minute intervals during exercise, and at 10 minutes recovery.

RESULTS: The PG displayed a significantly higher heart rate than the CG atrest, throughout exercise and during post-exercise recovery. Minute ventilation(VE ), VE/VCO2 andVE/VO2were all significantly elevated in the PG versus theCG throughout the exercise period. Alveolar oxygen tensions were higher andcarbon dioxide tensions were lower in the PG versus the CG at all observationaltimes. The respiratory exchange ratio (VCO2/VO2) was similar in the PG andthe CG under all experimental conditions. Tympanic temperature increased inthe CG from rest to 10 minutes of exercise and remained elevated throughoutthe exercise session. In contrast, temperature did not increase significantly inresponse to exercise in the PG.

CONCLUSION: Our findings support the hypothesis that prolonged,moderate intensity exercise is well tolerated by fit pregnant women undergoingnormal pregnancies.

Supported by Canadian Forces Personnel Support Agency.

hypertension is not present and CO is estimated to be low, afterload reductionmay enhance CO and increase renal perfusion and urine output